The present invention relates to a semiconductor device having a semiconductor element sealed with a resin, and more specifically, to a semiconductor device having a highly recyclable package. The present invention further relates to a thermoplastic resin composition excellent in adhesiveness to a carrier member such as a leadframe.
Conventionally, it is known that a semiconductor device is formed by mounting a semiconductor element on a leadframe and thereafter sealing the semiconductor element with a thermosetting resin. Such a semiconductor device is formed as follows.
A leadframe having a semiconductor element mounted thereon is placed in a cavity formed by combining an upper mold and a lower mold. The semiconductor element is electrically connected to the leadframe by, for example, a bonding wire. Then, an epoxy resin (thermosetting resin) is injected through an injection port (gate) facing within the cavity. The epoxy resin thus injected is heated to solidify, with the result that the semiconductor element and the leadframe are integrated into one body. As described, the thermosetting resin is widely employed in manufacturing the semiconductor device since the thermosetting resin has a good flowability and adhesiveness.
However, when the thermosetting resin is cured, nearly 60 seconds in average is required until a curing reaction is completed. Due to the long reaction, the semiconductor device decreases in productivity. In addition, since the flowability of the thermosetting resin is too high, burrs are easily produced. Furthermore, once the thermosetting resin is heated, original flowability cannot be brought back. Therefore, the thermosetting resin cannot be recycled. Consequently, when the semiconductor devices using the thermosetting resin become out of use, they have no choice but to be subjected to the land-fill disposal or incineration disposal.
To reduce the curing time, it is considered to use a thermoplastic resin in place of the thermosetting resin. When the thermoplastic resin is used, it is estimated to take 10 seconds for curing. If the thermoplastic resin is used, the original flowability of the thermoplastic resin can be brought back by heat treatment. The thermoplastic resin is therefore advantageous in view of the recycle use.
However, compared to the thermosetting resin, the thermoplastic resin has low adhesion properties to the leadframe, so that moisture contents and oily contents may enter through an interface between the leadframe and the resin. Since the thermoplastic resin has a problem of low moisture resistance, it has not conventionally been used.
In addition, the thermoplastic resin has a large linear expansion coefficient, so that stress is applied to the semiconductor element after solidification. As a result, cracks are produced in the semiconductor element.